Modular wave energy converter

ABSTRACT

A modular wave energy converter includes: a forward attachment frame; forward guide rails coupled to the forward attachment frame; a forward paddle coupled to the forward guide rails; and one or more forward tethers coupled to the forward paddle and the shaft. A combination of heave and surge forces from waves of water causes the forward paddle moves up and down the forward guide rails. The movement of the forward paddle moves the one or more forward tethers. The movement of the one or more forward tethers causes the shaft to rotate via the rotation of winches. The winches are configured with a one-way clutch, which allows the shaft to rotate in a first direction but not a second. The converter has the same structure on the aft side, including an aft paddle. The forward and aft paddles are positioned vertically or inclined.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to U.S. Provisional PatentApplication Ser. No. 63/270,711, entitled “On-Site Alternative PowerSolution for Aquaculture” and filed Oct. 22, 2021, and to U.S.Provisional Patent Application Ser. No. 63/264,669, entitled “ModularWave Energy Converter Retrofitted to Offshore Aquaculture Farms” andfiled on Nov. 30, 2021. The foregoing applications are incorporatedherein by reference in its entirety.

BACKGROUND OF THE INVENTION

Wave energy converters use either direct-drive power take-off system orindirect-drive power take-off systems. The conventional wave energyconverters with direct-drive power take-off systems typically use linearelectromagnetic generators without intermediate steps. These systems areheavy, inefficient, and expensive. Some wave energy converters withindirect-drive power take-off systems use hydraulic or pneumatic fluidto drive a rotational generator. The fluid drive of these systemsintroduces efficiency loss, increased complexity, and reducedreliability, especially when not in an ideal operating point. Some waveenergy converters with indirect-drive power take-off systems use rackpinions or ball screws. The mechanical drive of these systems provideshigh compactness and efficiency, but the cost and reliability in oceanenvironments are of concern.

BRIEF SUMMARY OF THE INVENTION

Disclosed herein are embodiment of a wave energy converter with forwardand aft paddles as specified in the independent claims. Embodiments ofthe present invention are given in the dependent claims. Embodiments ofthe present invention can be freely combined with each other if they arenot mutually exclusive.

According to one embodiment of the present invention, a modular waveenergy converter includes: a power take-off system, the power take-offsystem comprising a shaft, the shaft being coupled to a generator; aforward attachment frame coupled to a forward side; forward guide railscoupled to the forward attachment frame; a forward paddle coupled to theforward guide rails and configured to move up and down the forward guiderails; and one or more forward tethers coupled to the forward paddle andthe shaft. In response to a combination of heave and surge forces fromwaves of water, the forward paddle moves up and down the forward guiderails. The movement of the forward paddle moves the one or more forwardtethers. The movement of the one or more forward tethers causes theshaft to rotate. The rotation of the shaft causes the generator torotate and generate electricity.

In one aspect of the present invention, the modular wave energyconverter further includes: an aft attachment frame coupled to an aftside; aft guide rails coupled to the aft attachment frame; an aft paddlecoupled to the aft guide rails and configured to move up and down theaft guide rails; and one or more aft tethers coupled to the aft paddleand the shaft. In response to a combination of heave and surge forcesfrom waves of water, the aft paddle moves up and down the aft guiderails. The movement of the aft paddle moves the one or more aft tethers.The movement of the one or more aft tethers causes the shaft to rotate.The rotation of the shaft causes the generator to rotate and generateelectricity.

In another aspect of the present invention, the forward paddle ispositioned vertically.

According to another embodiment of the present invention, the forwardpaddle is inclined.

In another aspect of the present invention, the aft paddle is positionedvertically.

In another aspect of the present invention, the aft paddle is inclined.

According to another embodiment of the present invention, the modularwave energy converter includes: a power take-off system, the powertake-off system comprising a shaft, the shaft being coupled to agenerator; a forward attachment frame coupled to a forward side; aforward paddle; a forward hinge coupled to a lower portion of theforward attachment frame and a lower portion of the forward paddle; andone or more forward tethers coupled to the forward paddle and the shaft.In response to a combination of heave and surge forces from waves ofwater, the forward paddle pivots about the forward hinge. The movementof the forward paddle moves the one or more forward tethers. Themovement of the one or more forward tethers causes the shaft to rotate.The rotation of the shaft causes the generator to rotate and generateelectricity.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 illustrates a perspective view of a modular wave energyconverter.

FIGS. 2, 3, and 4 illustrate a side view, a top view, and a bottom view,respectively, of the modular wave energy converter.

FIG. 5 illustrates an end view at the forward side of the modular waveenergy converter.

FIG. 6 illustrates an exploded view of the modular wave energyconverter.

FIG. 7 illustrates the forward paddle in an upper position on theforward guide rails.

FIG. 8 illustrates the forward paddle in a lower position on the guiderails.

FIG. 9 illustrates a close-up view of the forward bottom pulleys.

FIG. 10 illustrates a close-up view of the forward upper pulleys.

FIG. 11 illustrates a close-up view of the winches of the power take-offsystem.

FIG. 12 is a block diagram illustrating the movement of the tethers whenthe forward paddle moves up the forward guide rails.

FIG. 13 is a block diagram illustrating the movement of the tethers whenthe forward paddle moves down the forward guide rails.

FIGS. 14A-B, 15, and 16 illustrate a top view, a front view, and a backview of the power take-off system, respectively.

FIGS. 17A-17C illustrates the wave-paddle interaction for the modularwave energy converter.

FIGS. 18, 19, and 20 illustrate a perspective view, a side view, and atop view, respectively, of a second alternative embodiment of themodular wave energy converter.

FIGS. 21 and 22 illustrate a side view and a top view, respectively, ofa third alternative embodiment of the modular wave energy converter.

FIG. 23 illustrates a perspective view of a first alternative embodimentof the modular wave energy converter.

DETAILED DESCRIPTION OF THE INVENTION

The present invention provides a modular wave energy converter. Thefollowing description is presented to enable one of ordinary skill inthe art to make and use the present invention and is provided in thecontext of a patent application and its requirements. Variousmodifications to the embodiment will be readily apparent to thoseskilled in the art and the generic principles herein may be applied toother embodiments. Thus, the present invention is not intended to belimited to the embodiment shown but is to be accorded the widest scopeconsistent with the principles and features described herein.

Reference in this specification to “one embodiment,” “an embodiment,”“an exemplary embodiment,” “some embodiments,” or “a preferredembodiment” means that a particular feature, structure, orcharacteristic described in connection with the embodiment is includedin at least one embodiment of the invention. The appearances of thephrase “in one embodiment” in various places in the specification arenot necessarily all referring to the same embodiment, nor are separateor alternative embodiments mutually exclusive of other embodiments.Moreover, various features are described which may be exhibited by someembodiments and not by others. Similarly, various requirements aredescribed which may be requirements for some embodiments but not otherembodiments. In general, features described in one embodiment might besuitable for use in other embodiments as would be apparent to thoseskilled in the art.

The Figures use the following reference numerals:

-   101 Feed buoy-   102 a-102 b Forward and aft attachment frames-   103 a-103 b Forward and aft paddles-   104 a-104 b Forward and aft support trusses-   105 a-105 b Forward and aft tethers-   106 a-106 b Forward and aft lower pulleys-   107 a-107 b Forward and aft upper pulleys-   108 Power take-off system-   109 Clamps-   110 Crossbars-   111 a-111 b Forward and aft guide rails-   112 a-112 b Forward and aft sleeves-   113 a-113 b Forward and aft guide rail connectors-   114 Cross frame-   301 a-301 b First set of forward tethers-   301 a driving tether of first forward set-   301 b retrieval tether of first forward set-   302 a-302 b Second set of forward tethers-   302 a driving tether of second forward set-   302 b retrieval tether of second forward set-   311 a-311 b First set of aft tethers-   311 a driving tether of first aft set-   311 b retrieval tether of first aft set-   312 a-312 b Second set of aft tethers-   312 a driving tether of second aft set-   312 b retrieval tether of second aft set-   901 Connection for retrieval tether 301 b of first forward set-   902 Port for retrieval tether 301 b of first forward set-   903 Connection for driving tether 302 a of second forward set-   904 Port for driving tether 302 a of second forward set-   905 Connection for driving tether 301 a of first forward set-   906 Connection for retrieval tether 302 b of second forward set-   BP1-BP2 Bottom pulleys in forward lower pulleys 106 a-   UP1-UP4 Upper pulleys in forward upper pulleys 107 a-   1101 First set of winches for forward paddle 103 a-   1102 Second set of winches for aft paddle 103 b-   1110 First winch of the first set of winches-   1120 Second winch of the first set of winches-   W1 First winch portion of the first winch-   W2 Second winch portion of the first winch-   W3 First winch portion of the second winch-   W4 Second winch portion of the second winch-   1401 First shaft coupler of power take-off system 108-   1402 Gearbox of power take-off system 108-   1403 Second shaft coupler of power take-off system 108-   1404 Generator of power take-off system 108-   1405 Housing of power take-off system 108    -   1405 a First side cover    -   1405 b Base plate    -   1405 c Top cover    -   1405 d Second side cover-   1406 Ball bearings-   1407 One-way clutches-   1408 a-1408 b First and second shafts-   1409 Drainage holes-   1801 a-1801 b Forward and aft paddles for the second alternative    embodiment-   1802 a-1802 b Forward and aft tethers for the second alternative    embodiment-   1803 a-1803 b Forward and aft trusses for the second alternative    embodiment-   1804 a-1804 b Forward and aft attachment frames for the second    alternative embodiment-   1805 a-1805 b Forward and aft guide rails for the second alternative    embodiment-   1806 a-1806 b Forward and aft sleeves for the second alternative    embodiment-   2101 a-2101 b Forward and aft flaps for the third alternative    embodiment-   2102 a-1202 b Forward and aft tethers for the third alternative    embodiment-   2103 a-2103 b Forward and aft hingers for the third alternative    embodiment-   2104 a-2104 b Forward and aft attachment frames for the third    alternative embodiment-   2301 a-2301 b Forward and aft paddles for the first alternative    embodiment

FIG. 1 illustrates a perspective view of a modular wave energyconverter. FIGS. 2, 3 , and 4 illustrate a side view, a top view, and abottom view, respectively. FIG. 5 illustrates an end view at the forwardside. The end view at the aft side is a mirror of the end view at theforward side. FIG. 6 illustrates an exploded view of the modular waveenergy converter. The modular wave energy converter (WEC) is coupled toa feed buoy 101. The feed buoy 101 can be an existing platform, wherethe WEC is retrofitted onto the platform 101. The feed buoy platformincludes crossbars 110 coupled to the feed buoy 101 via clamps 109. Across frame 114 provides additional structural integrity to theplatform.

Coupled to a forward side of the feed buoy 101, via a forward attachmentframe 102 a, is a forward paddle 103 a. Coupled to an aft side of thefeed buoy 101, via an aft attachment frame 102 b, is an aft paddle 103b. The forward paddle 103 a is coupled to the forward attachment frame102 a via inclined forward guide rails 111 a. In this embodiment, theforward paddle 103 a is oriented in a vertical position. At theinterface between the forward paddle 103 a and the forward guide rails111 a are forward sleeves 112 a. The forward support trusses 104 a arecoupled to the forward paddle 103 a on one end and coupled to theforward sleeves 112 a on the other end. The forward guide rails 111 aare coupled to the forward attachment frame 102 a via forward guide railconnectors 113 a. The forward paddle 103 a is able to move up and downthe forward guide rails 111 a. Similarly, the aft paddle 103 b iscoupled to the aft attachment frame 102 b via inclined aft guide rails111 b. In this embodiment, the aft paddle 103 b is oriented in avertical position. At the interface between the aft paddle 103 b and theaft guide rails 111 b are aft sleeves 112 b. The aft paddle 103 b iscoupled to the aft sleeves 112 b. The aft support trusses 104 b arecoupled to the aft paddle 103 b on one end and coupled to the aftsleeves 112 b on the other end. The aft guide rails 111 b are coupled tothe aft attachment frame 102 b via aft guide rail connectors 113 b. Theaft paddle 103 b is able to move up and down the aft guide rails 111 b.

On the forward side, the WEC further includes a first set of forwardtethers 301 a-301 b and a second set of forward tethers 302 a-302 b.(See FIG. 3 .) The first set of forward tethers includes a drivingtether 301 a and a retrieval tether 301 b. The second set of forwardtethers includes a driving tether 302 a and a retrieval tether 302 b.The retrieval tether 301 b of the first forward set and the drivingtether 302 a of the second forward set are coupled to forward lowerpulleys 106 a. The first and second sets of forward tethers 301 a-301 band 302 a-302 b are coupled to and traverse forward upper pulleys 107 aand are coupled to the power take-off system 108. The first and secondsets of forward tethers 301 a-301 b and 302 a-302 b move when theforward paddle 103 a moves, and this movement is used to generate power,as described further below.

On the aft side, the WEC further includes a first set of aft tethers 311a-311 b and a second set of aft tethers 312 a-312 b. The first set ofaft tethers includes a driving tether 311 a and a retrieval tether 311b. The second set of aft tethers also includes a driving tether 312 aand a retrieval tether 312 b. The retrieval tether 311 b of the firstaft set and the driving tether 312 a of the second aft set are coupledto aft lower pulleys 106 b. The first and second sets of aft tethers 311a-311 b and 312 a-312 b are coupled to and traverse aft upper pulleys107 b and coupled to the power take-off system 108. The first and secondsets of aft tethers 311 a-311 b and 312 a-312 b move when the aft paddle103 b moves, and this movement is used to generate power, as describedfurther below.

When deployed, the feed buoy is coupled to a mooring system (not shown),where the forward and aft paddles 103 a-103 b are partially submerged.Line A in FIG. 1 illustrates an example water line. The WEC ispositioned such that the forward and aft paddles 103 a-103 b are excitedby incident waves and oscillate along the forward and aft guide rails111 a-111 b.

FIG. 7 illustrates the forward paddle 103 a in an upper position on theforward guide rails 111 a. When a wave exerts an upwards heave force onthe forward paddle 103 a, the upwards heave force accelerates theforward paddle 103 a up the forward guide rails 111 a. FIG. 8illustrates the forward paddle 103 a in a lower position on the guiderails 111 a. When the wave exerts a downward heave force on the forwardpaddle 103 a, the downward heave force accelerates the forward paddle103 a down the forward guide rails 111 a. The aft paddle 103 b moves upand down the aft guide rails 111 b in the same manner as the forwardpaddle 103 a.

FIG. 9 illustrates a close-up view of the forward bottom pulleys 106 a.As illustrated in FIG. 9 , the forward bottom pulleys 106 a include afirst bottom pulley (BP1) and a second bottom pulley (BP2). FIG. 10illustrates a close-up view of the upper pulleys 107 a. As illustratedin FIG. 10 , the upper pulleys 107 a include a first upper pulley (UP1),a second upper pulley (UP2), a third upper pulley (UP3), and a fourthupper pulley (UP4). FIG. 11 illustrates a close-up view of the winches1101-1102 of the power take-off system 108. As illustrated in FIG. 11 ,a first set of winches 1101 includes a first winch 1110 and a secondwinch 1120. The first winch 1110 includes a first winch portion W1 and asecond winch portion W2. The second winch 1120 includes a first winchportion (W3) and a second winch portion (W4). The winch portions W1 andW2 are fixably attached to each other. The winch portions W3 and W4 arefixably attached to each other. The driving tether 301 a is coupled towinch portion W1 and wraps around winch portion W1 in a first direction.The retrieval tether 301 b is coupled to winch portion W2 and wrapsaround winch portion W2 in a second direction. The driving tether 302 ais coupled to winch portion W3 and wraps around winch portion W3 in thefirst direction. The retrieval tether 302 b is coupled to winch portionW4 and wraps around winch portion W4 in the second direction. The winch1110 is coupled to a shaft 1408 a (see FIG. 14B) in the power take-offsystem 108 via a one-way clutch 1407 (see FIG. 14B). The winch 1120 iscoupled to the shaft 1408 a in the power take-off system 108 via anotherone-way clutch 1407. The one-way clutches 1407 are configured to allowthe shaft 1408 a to rotate in the first direction, but not the seconddirection. Thus, a “one-way clutch,” as used herein, refers to anymechanism which would allow the shaft to rotate in one direction but notthe opposite direction. When the winch 1110 or 1120 is turned in thefirst direction due to movement of any combination of the tethers 301a-301 b, 302 a-302 b, the one-way clutch 1407 between the winch 1110 orwinch 1120 and the shaft 1408 a is engaged, and the shaft 1408 a isturned in the first direction. The rotation of the shaft 1408 a causesthe generator 1404 of the power take-off system 108 (see FIGS. 14A-14B)to rotate and generate electricity. However, when either the winch 1110or the winch 1120 is turned in the second direction due to movement ofany combination of the tethers 301 a-301 b, 302 a-302 b, the one-wayclutch 1407 between the winch 1110 or the winch 1120 and the shaft 1408a is disengaged, and the shaft 1408 a does not turn.

Referring to FIGS. 9, 10, 11, and 12 , the retrieval tether 301 b of thefirst forward set is coupled to an outer face of the forward paddle 103a at location 901. The retrieval tether 301 b engages the bottom pulleyBP1, traverses the bottom pulley BP1, and continues to traverse throughthe forward paddle 103 a through a port 902. On the inside face of theforward paddle 103 a, the retrieval tether 301 b exits the port 902,engages and traverses the upper pulley UP2, and couples to winch portionW2.

The driving tether 301 a of the first forward set is coupled to aninside face of the forward paddle 103 a at location 905. The drivingtether 301 a engages and traverses the upper pulley UP1 and continues tocouple to winch portion W1.

The driving tether 302 a of the second forward set is coupled to anouter face of the forward paddle 103 a at location 903. The drivingtether 302 a engages and traverses the bottom pulley BP2 and continuesto traverse through the forward paddle 103 a through a port 904. On theinside face of the forward paddle 103 a, the driving tether 302 a exitsthe port 904, engages and traverses the upper pulley UP3, and couples towinch portion W3.

The retrieval tether 302 b of the second forward set is coupled to aninside face of the forward paddle 103 a at location 906. The retrievaltether 302 b engages and traverses the upper pulley UP4 and continues tocouple to winch portion W4.

The first and second sets of aft tethers 311 a-311 b and 312 a-312 bengages the aft lower pulleys 106 b, the aft upper pulleys 107 b, andthe winches 1102 in the same manner.

FIG. 12 is a block diagram illustrating the movement of the tethers 105a when the forward paddle 103 a moves up the forward guide rails 111 a.FIG. 13 is a block diagram illustrating the movement of the tethers 105a when the forward paddle 103 a moves down the forward guide rails 111a. For illustrative purposes, only the forward paddle 103 a, the forwardtethers (301 a-301 b, 302 a-302 b), the forward pulleys (BP1-BP2,UP1-UP4), and the winches 1110, 1120 are shown. Referring to FIG. 12 ,when the forward paddle 103 a moves up the forward guide rails 111 a,the portion of the driving tether 302 a coupled between the forwardpaddle 103 a at location 903 and the bottom pulley BP2 is pulled upward.This causes the portion of the driving tether 302 a coupled between thebottom pulley BP2 and the upper pulley UP3 to move downward, causing thedriving tether 302 a to unwind from the winch portion W3, and causingthe winch portion W3 to rotate in the first direction. This in turnengages the one-way clutch 1407, which is between the winch 1120 and theshaft 1408 a and causes the shaft 1408 a to rotate in the firstdirection, resulting in the generation of power. The rotation of winchportion W3 in the first direction also rotates the winch portion W4 inthe first direction, since winch portions W3 and W4 are fixably attachedto each other, causing the retrieval tether 302 b to wind onto the winchportion W4. The movement up the forward guide rails 111 a also causesthe retrieval tether 301 b coupled between the forward paddle 103 a atlocation 901 and the bottom pulley BP1 to be pulled upward. This causesthe portion of the retrieval tether 301 b coupled between the bottompulley BP1 and the upper pulley UP2 to move downward, causing theretrieval tether 301 b to unwind from the winch portion W2, and causingthe winch portion W2 to rotate in the second direction. The rotation ofwinch portion W2 in the second direction also rotates the winch portionW1 in the second direction, since winch portions W2 and W1 are fixablyattached to each other, causing the driving tether 301 a to wind ontothe winch portion W1. The rotation of the winch portion W2 in the seconddirection disengages the one-way clutch 1407 coupled between the winch1110 and the shaft 1408 a, and the shaft 1408 a does not rotate.

Referring to FIG. 13 , when the forward paddle 103 a moves down theforward guide rails 111 a, the portion of the driving tether 301 acoupled between the forward paddle 103 a at location 905 and the winchportion W1 is pulled downward, causing the winch portion W1 to rotate inthe first direction. This in turn engages the one-way clutch 1407coupled between the winch 1110 and the shaft 1408 a and causes the shaft1408 a to rotate in the first direction, resulting in the generation ofpower. The rotation of winch portion W1 in the first direction alsorotates the winch portion W2 in the first direction, since winchportions W1 and W2 are fixably attached to each other, causing theretrieval tether 301 b to wind onto the winch portion W2. The movementdown the forward guide rails 111 a also causes the retrieval tether 302b coupled between the forward paddle 103 a at location 906 and the winchportion W4 is pulled downward, causing the retrieval tether 302 b tounwind from the winch portion W4, and causing the winch portion W4 torotate in the second direction. The rotation of winch portion W4 in thesecond direction also rotates the winch portion W3 in the seconddirection, since winch portions W3 and W4 are fixably attached to eachother, causing the driving tether 302 a to wind onto the winch portionW3. The rotation of winch portion W4 in the second direction disengagesthe one-way clutch 1407 coupled between the winch 1120 and the shaft1408 a, and the shaft 1408 a does not rotate.

Thus, when the forward paddle 103 a moves up the forward guide rails 111a, the second set of forward tethers 302 a-302 b results in thegeneration of power. When the forward paddle 103 a moves down theforward guide rails 111 a, the first set of forward tethers 301 a-301 bresults in the generation of power. In this manner, the WEC generatespower with both up and down movements of the forward paddle 103 a.

The movements of the aft paddle 103 b and the first and second set ofaft tethers 311 a-311 b, 312 a-312 b result in the generation of powerin the same manner as described above with the forward paddle 103 a.

FIGS. 14A-B, 15, and 16 illustrate a top view, a front view, and a backview of the power take-off system, respectively. The power take-offsystem 108 includes a first set of winches 1101 and a second set ofwinches 1102. The first set of winches 1101 engage the forward tethers105 a, and the second set of winches 1102 engage the aft tethers 105 b.Traversing through the length of the power take-off system 108 areshafts 1408 a-1408 b. Coupled to the first shaft 1408 a is a set of ballbearings 1406 and one-way clutches 1407. The ball bearings 1406 canrotate in either direction and acts as a connection point between thefirst shaft 1408 a and the housing 1405 and between the first shaft 1408a and the winches 1101-1102. The one-way clutches 1407 engage with thefirst shaft 1408 a in the first direction and disengage from the firstshaft 1408 a in the second direction, which is opposite the firstdirection. The one-way clutches 1407 reside between the first shaft 1408a and winches 1101-1102. There is one one-way clutch 1407 within thewinch 1110 and another one-way clutch 1407 within the winch 1120. Thefirst shaft 1408 a is coupled to a gearbox 1402 via a first shaftcoupler 1401. The second shaft 1408 b is coupled to the gearbox 1402 viaa keyway connection and to a generator 1404 via a second shaft coupler1403. The components of the power take-off system 108 resides within ahousing 1405 that includes a first side cover 1405 a, a base plate 1405b, a top cover 1405 c, and a second side cover 1405 d. The base plate1405 b includes a plurality of drainage holes 1409 to drain any seawaterthat enters the housing 1405.

The total water-related force on each paddle 103 a-103 b are composed ofhydrostatic force, hydrodynamic force, and viscous force. Thehydrostatic force provides restoring force on the paddles 103 a-103 b totheir initial equilibrium position. The hydrodynamic force providesexcitation force, and the viscous force provides damping to the paddlemotion. When waves approach the forward and then aft paddles 103 a-103b, the hydrodynamic force, which is a combination of both heave andsurge forces, moves the paddles 103 a-103 b on their respective guiderails 111 a-111 b. FIGS. 17A-17C illustrates the wave-paddle interactionfor the modular wave energy converter. The heave force references up anddown force (z-direction) while the surge force references left and rightforce (x-direction). FIG. 17A illustrates the motion of the wave as thewave travels. FIG. 17B illustrates the force exerted on the forwardpaddle 103 a by the wave. FIG. 17C illustrates the force exerted on theaft paddle 103 b by the wave. Note that the diagrams do not fullyaccount of the feed buoy 101 itself. As the wave approaches at point 1,the wave exerts an upwards heave force on the forward paddle 103 a,causing the forward paddle 103 a to accelerate up the forward guiderails 111 a, as depicted by the solid semi-circle in FIG. 17B. Betweenpoints 1 and 2, the forward paddle 103A experiences a combination of anupwards heave force and a surge force towards the aft. During thisphase, the forward paddle 103 a undergoes its maximum linearacceleration of the cycle up the forward guide rails 111 a. At point 2,the wave exerts a surge force towards the aft on the forward paddle 103a and continues to cause the forward paddle 103 a to accelerate up theforward guide rails 111 a. Between points 2 and 3, the forward paddle103 a experiences a combination of a downwards heave force and a surgeforce towards the aft. During this phase, the forward paddle 103 aundergoes a point where the acceleration is zero, since the surge andheave forces cancel each other out. This phase also marks the transitionfrom accelerating up to accelerating down the forward guide rails 111 a.At point 3, the wave exerts a downwards heave force on the forwardpaddle 103 a, causing the forward paddle 103 a to continue to acceleratedown the forward guide rails 111 a. The phase in which the forwardpaddle 103 a experiences an acceleration down the forward guide rails111 a is depicted by the dotted semi-circle in FIG. 17B. Between points3 and 4, the forward paddle 103 a experiences a combination of adownwards heave force and a surge force towards the forward. During thisphase, the forward paddle 103 a undergoes its maximum linearacceleration of the cycle down the forward guide rails 111 a. At point4, the wave exerts a surge force towards the forward on the forwardpaddle 103 a, causing the forward paddle 103 a to continue to acceleratedown the forward guide rail 111 a. The cycle ends betweens points 4 and1, as the forward paddle 103 a experiences a combination of an upwardsheave force and a surge force towards the forward. During this phase,the forward paddle 103 a undergoes a point where the acceleration iszero on the forward paddle 103 a as the surge and heave forces canceleach other out. Then the cycle starts anew at point 1.

The wave-paddle interaction on the aft paddle 103 b is the similar tothe wave-paddle interaction on the forward paddle 103 a but phaseshifted, as illustrated in FIG. 17C. Illustrated in FIG. 17C is thephase between points 1 and 2, in which the aft paddle 103 b experiencesa point of zero acceleration instead of maximum acceleration. When thesurge force is towards the aft, it opposes the upwards heave force,causing the two to cancel out.

The forward and aft paddles 103 a-103 b enables the WEC to resonate withthe incident waves, even with a small scale, e.g., 4 meters wide. TheWEC harvests the wave energy in both heave and surge directions,allowing for an improved capture width ratio. By adjusting theunderwater length and thickness of the forward and aft paddles 103 a-103b, the WEC's natural period can be tuned to any desired peak waveperiods in the ocean. The WEC may be moored close to the coastline,where waves travel in one direction, and aligned with the direction oftravel for the waves in order to maximize the power conversion. Thesymmetrical design of the WEC, with forward and aft paddles 103 a-103 bassist in maximizing the power conversation and also provides a loadbalanced structure. With the forward and aft paddles 103 a-103 boriented in vertical positions, their respective movements along theforward and aft guide rails 111 a-111 b are also maximized, in turnfurther assisting in maximizing the power conversion. By using thetether-and-winch system to drive the generator and converting thedual-directional motions of the forward and aft paddles 103 a-103 b intouni-directional motion of the power generator, the modular wave energyconverter can achieve a higher power conversion efficiency as comparedto conventional wave energy converters at a similar. The WEC is furtherconfigured to attach onto existing floating and fixed infrastructure,such as the feed buoy 101, which allows the WEC to be implemented at alower capital cost. By leveraging existing infrastructure, costsassociated with surveying, permitting, environmental monitoring, andmooring and anchor installation are removed. Further, costs associatedwith installation and maintenance that requires underwater vehicles anddivers are also reduced, as only the bottom portion of the paddles 103a-103 b and attachment frames 102 a-102 b are submerged while beingclose to the surface of the water. Line A in FIG. 1 illustrates anapproximate water line. The power take-off system 108 remains above thewaterline A, making maintenance simpler and at a lower cost.

Although the WEC is described above with the paddle and itscorresponding components at both the forward and aft sides, a paddle andcorresponding components may be implemented at only the forward side oronly at the aft side.

FIG. 23 illustrates a perspective view of a first alternative embodimentof the modular wave energy converter. In this embodiment, the forwardpaddle 2301 a and the aft paddle 2301 b are inclined instead of beingpositioned vertically. The other components of the first alternativeembodiment are the same as the embodiment illustrated above andgenerates power through both the upward and downward movements of thepaddles 2103 a-2103 b, as described above.

FIGS. 18, 19, and 20 illustrate a perspective view, a side view, and atop view, respectively, of a second alternative embodiment of themodular wave energy converter. In the alternative embodiment, theforward paddle 1801 a and the aft paddle 1801 b are inclined. Theforward paddle 1801 a is coupled to the forward attachment frame 1804 avia inclined forward guide rails 1805 a. At the interface between theforward paddle 1801 a and the forward guide rails 1805 a are forwardsleeves 1806 a. The forward support trusses 1803 a are coupled to theforward paddle 1801 a on one end and coupled to the forward sleeves 1806a on the other end. One end of a forward tether 1802 a is coupled to aninside face of the forward paddle 1801 a, and the other end of theforward tether 1802 a is coupled to a winch (not shown) of the powertake-off system 108. The forward paddle 1801 a moves up and down theforward guide rails 1805 a. Similarly, the aft paddle 1801 b is coupledto the aft attachment frame 1804 b via inclined aft guide rails 1805 b.At the interface between the aft paddle 1801 b and the aft guide rails1805 b are aft sleeves 1806 b. The aft support trusses 1803 b arecoupled to the aft paddle 1801 b on one end and coupled to the aftsleeves 1806 a on the other end. One end of an aft tether 1802 b iscoupled to an inside face of the aft paddle 1801 b, and the other end ofthe aft tether 1802 b is coupled to the power take-off system 108. Theaft paddle 1801 b moves up and down the aft guide rails 1805 b. In thealternative embodiment, the WEC interfaces with the waves and generatespower in a similar manner as described above with reference to FIGS.17A-17C. In the alternative embodiment, since the paddles 1801 a-1801 bare inclined, their movements up and down the guide rails 1805 a-1805 bhave lesser ranges than the vertically positioned paddles 103 a-103 b.

FIGS. 21 and 22 illustrate a side view and a top view, respectively, ofa third alternative embodiment of the modular wave energy converter. Inthe second alternative embodiment, the forward paddle 2101 a and the aftpaddle 2101 b are flap-type paddles. The forward paddle 2101 a iscoupled to the forward attachment frame 2104 a via a forward hinge 2103a. One end of a forward tether 2102 a is coupled to an inside face ofthe forward paddle 2101 a, and the other end of the forward tether 2102a is coupled to the power take-off system 108. The forward paddle 2101 apivots about the hinge 2103 a. Similarly, the aft paddle 2101 b iscoupled to the aft attachment frame 2104 b via an aft hinge 2103 b. Oneend of an aft tether 2102 b is coupled to an inside face of the aftpaddle 2101 b, and the other end of the aft tether 2102 b is coupled tothe power take-off system 108.

In the third alternative embodiment, the WEC interfaces with the wavesand generates power in a similar manner as described above in that, whenthe forward and aft tethers 2101 a-2101 b are pulled, this rotates awinch (not shown) in the power take-off system 108, which in turnsdrives the power generator of the power take-off system 108. Inresonance, the forward and aft paddles 2101 a-2101 b pivot upwards whilethe feed buoy 101 moves down. The forward and aft paddles 2101 a-2101 bpivot downwards while the feed buoy 101 moves up. With reference toFIGS. 17A-17C, when the wave approaches at point 1, the wave exerts anupwards pitch force on the forward paddle 2101 a, causing the forwardpaddle 2101 a to experience acceleration upwards and towards the feedbuoy 101, as depicted by the solid semi-circle in FIG. 17B. Betweenpoints 2 and 3, the forward paddle 2101 a reaches a maximum angularacceleration of the cycle, pivoting towards the feed buoy 101. At point2, the wave continues to exert a pitch force on the forward paddle 2101a and continues to cause the forward paddle 2101 a to pivot towards thefeed buoy 101. Between steps 2 and 3, the forward paddle 2101 atransitions from a pitch force that is upwards and towards the feed buoy101 to a pitch force that is downwards and away from the feed buoy 101.The angular acceleration reaches zero during this phase. At point 3, thewave exerts a downwards pitch force, causing the forward paddle 2101 ato pivot away from the feed buoy 101, as depicted by the dottedsemi-circle in FIG. 17B. Between points 3 and 4, the forward paddle 2101a reaches maximum angular acceleration of the cycle, downwards and awayfrom the feed buoy 101. At point 4, the wave continues to exert a pitchforce on the forward paddle 2101 a and continues to cause the forwardpaddle 2101 a to pivot away from the feed buoy 101. The cycles endbetween steps 4 and 1 as the forward paddle 2101 a transitions from apitch force that is downwards and away from the feed buoy 101 to a pitchforce that is upwards and towards the feed buoy 101. The angularacceleration reaches zero during this phase. Then the cycle starts anewat point 1.

The forces on the aft paddle 2101 b are the same as the forward paddle2101 a but phase shifted, as illustrated in FIG. 17C. Illustrated inFIG. 17C is the phase between points 1 and 2, in which the aft paddle2101 b experiences a point of zero acceleration instead of maximumacceleration. When the surge force is towards the aft, it opposes theupwards heave force, causing the two to cancel out.

It should be understood that the exemplary embodiments described hereinshould be considered in a descriptive sense only and not for purposes oflimitation. Descriptions of features or aspects within each embodimentshould typically be considered as available for other similar featuresor aspects in other embodiments. While one or more embodiments have beendescribed with reference to the figures, it will be understood by thoseof ordinary skill in the art that various changes in form and detailsmay be made therein without departing from their spirit and scope.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of the invention. Asused herein, the singular forms “a,” “an” and “the” are intended toinclude the plural forms as well, unless the context clearly indicatesotherwise. It will be further understood that the terms “comprises”and/or “comprising,” when used in this specification, specify thepresence of stated features, integers, steps, operations, elements,and/or components, but do not preclude the presence or addition of oneor more other features, integers, steps, operations, elements,components, and/or groups thereof.

Although the present invention has been described in accordance with theembodiments shown, one of ordinary skill in the art will readilyrecognize that there could be variations to the embodiments and thosevariations would be within the spirit and scope of the presentinvention. Accordingly, many modifications may be made by one ofordinary skill in the art without departing from the spirit and scope ofthe appended claims.

What is claimed is:
 1. A modular wave energy converter, comprising: apower take-off system, the power take-off system comprising a shaft, theshaft being coupled to a generator; a forward attachment frame coupledto a forward side; forward guide rails coupled to the forward attachmentframe; a forward paddle coupled to the forward guide rails andconfigured to move up and down the forward guide rails; and one or moreforward tethers coupled to the forward paddle and the shaft, wherein theone or more forward tethers comprises: a driving tether of a firstforward set, a retrieval tether of the first forward set, a drivingtether of a second forward set, and a retrieval tether of the secondforward set, wherein in response to a combination of heave and surgeforces from waves of water, the forward paddle moves up and down theforward guide rails, wherein the movement of the forward paddle movesthe one or more forward tethers, wherein the movement of the one or moreforward tethers causes the shaft to rotate.
 2. The converter of claim 1,wherein the forward paddle is positioned vertically.
 3. The converter ofclaim 1, further comprising: a first forward bottom pulley and a secondforward bottom pulley coupled to a lower portion of the forwardattachment frame; a first forward upper pulley, a second forward upperpulley, a third forward upper pulley, and a fourth forward upper pulleycoupled to an upper portion of the forward attachment frame; and thepower take-off system comprising a first winch and a second winch, thefirst winch comprising a first winch portion fixably coupled to a secondwinch portion, the second winch comprising a third winch portion fixablycoupled to a fourth winch portion, wherein the first winch and thesecond winch are coupled to one-way clutches, wherein the one-wayclutches are coupled to the shaft, wherein the shaft is configured torotate in a first direction but not in a second direction.
 4. Theconverter of claim 3, further comprising: first one-way clutch coupledto the first winch and the shaft, and second one-way clutch coupled tothe second winch and the shaft, wherein the first and second one-wayclutches are configured to allow the shaft to rotate in the firstdirection and not allow the shaft to rotate in the second direction. 5.The converter of claim 4, wherein the forward paddle comprises a firstport and a second port, wherein the driving tether of the first forwardset is coupled to a first location on an inside face of the forwardpaddle, engages and traverses the first forward upper pulley, andcouples to a first winch portion, wherein the driving tether of thefirst forward set is wound onto the first winch portion in a firstdirection, wherein the retrieval tether of the first forward set iscoupled to a second location on an outside face of the forward paddle,engages and traverses the first forward bottom pulley, traverses throughthe first port and exits the inside face of the forward paddle, engagesand traverses the second forward upper pulley, and couples to a secondwinch portion, wherein the retrieval tether of the first forward set iswound onto the second winch portion in a second direction, wherein thedriving tether of the second forward set is coupled to a third locationon the outside face of the forward paddle, engages and traverses thesecond forward bottom pulley, traverse through the second port and exitsthe inside face of the forward paddle, engages and traverse the thirdforward upper pulley, and coupled to a third winch portion, wherein thedriving tether of the second forward set is wound onto the third winchportion in the first direction, wherein the retrieval tether of thesecond forward set is coupled to a fourth location on the inside face ofthe forward paddle, engages and traverses the fourth forward upperpulley, and coupled to a fourth winch portion, wherein the retrievaltether of the second forward set is wound onto the fourth winch portionin the second direction.
 6. The converter of claim 5, wherein when theforward paddle moves up the forward guide rails, the driving tether ofthe second forward set causes the third winch portion to rotate in thefirst direction, wherein the rotation of the third winch portion in thefirst direction causes the shaft to rotate in the first direction,wherein the rotation of the shaft in the first direction generateselectricity through the power generator, wherein the rotation of thethird winch portion in the first direction causes the fourth winchportion to rotate in the first direction, wherein the rotation of thefourth winch portion in the first direction causes the retrieval tetherof the second forward set to wind onto the fourth winch portion, whereinthe retrieval tether of the first forward set causes the second winchportion to rotate in the second direction, wherein the first one-wayclutch prevents the rotation of the shaft when the second winch portionrotates in the second direction, wherein the rotation of the secondwinch portion in the second direction causes the first winch portion torotate in the second direction, and the rotation of the first winchportion in the second direction causes the driving tether of the firstforward set to wind onto the first winch portion.
 7. The converter ofclaim 6, wherein when the forward paddle moves down the forward guiderails, the driving tether of the first forward set causes the firstwinch portion to rotate in the first direction, wherein the rotation ofthe first winch portion in the first direction causes the shaft torotate in the first direction, wherein the rotation of the shaft in thefirst direction generates electricity through the power generator,wherein the rotation of the first winch portion in the first directioncauses the second winch portion to rotate in the first direction,wherein the rotation of the second winch portion in the first directioncauses the retrieval tether of the first forward set to wind onto thesecond winch portion, wherein the retrieval tether of the second forwardset causes the fourth winch portion to rotate in the second direction,wherein the second one-way clutch prevents the rotation of the shaftwhen the fourth winch portion rotates in the second direction, whereinthe rotation of the fourth winch portion in the second direction causesthe third winch portion to rotate in the second direction, and whereinthe rotation of the third winch portion in the second direction causesthe driving tether of the second forward set to wind onto the thirdwinch portion.
 8. The converter of claim 1, wherein the forward paddleis inclined.
 9. A modular wave energy converter, comprising: a powertake-off system, the power take-off system comprising a shaft, the shaftbeing coupled to a generator; a forward attachment frame coupled to aforward side; an aft attachment frame coupled to an aft side; forwardguide rails coupled to the forward attachment frame; aft guide railscoupled to the aft attachment frame; a forward paddle coupled to theforward guide rails and configured to move up and down the forward guiderails; an aft paddle coupled to the aft guide rails and configured tomove up and down the aft guide rails; one or more forward tetherscoupled to the forward paddle and the shaft; one or more aft tetherscoupled to the aft paddle and the shaft, wherein in response to acombination of heave and surge forces from waves of water, the forwardpaddle moves up and down the forward guide rails and the aft paddlemoves up and down the aft guide rails, wherein the movement of theforward paddle moves the one or more forward tethers and the movement ofthe aft paddle moves the one or more aft tethers, wherein the movementof the one or more forward tethers and the one or more aft tetherscauses the shaft to rotate.
 10. The converter of claim 9, wherein themovement of the aft paddle in response to the combination of the heaveand the surge forces is phase shifted from the movement of the forwardpaddle.
 11. The converter of claim 9, wherein the one or more afttethers comprises: a driving tether of a first aft set, a retrievaltether of the first aft set, a driving tether of a second aft set, and aretrieval tether of the second aft set.
 12. The converter of claim 11,further comprising: a first aft bottom pulley and a second aft bottompulley coupled to a lower portion of the aft attachment frame; a firstaft upper pulley, a second aft upper pulley, a third aft upper pulley,and a fourth aft upper pulley coupled to an upper portion of the aftattachment frame; and the power take-off system comprising a first aftwinch and a second aft winch, the first aft winch comprising a first aftwinch portion fixably coupled to a second aft winch portion, the secondwinch comprising a third aft winch portion fixably coupled to a fourthaft winch portion, wherein the first aft winch and the second aft winchare coupled to one-way clutches, wherein the one-way clutches arecoupled to the shaft, wherein the shaft is configured to rotate in afirst direction but not in a second direction.
 13. The converter ofclaim 12, further comprising: first aft one-way clutch coupled to thefirst aft winch and the shaft, and second aft one-way clutch coupled tothe second aft winch and the shaft, wherein the first and second aftone-way clutches are configured to allow the shaft to rotate in thefirst direction and not allow the shaft to rotate in the seconddirection.
 14. The converter of claim 13, wherein the aft paddlecomprises a first aft port and a second aft port, wherein the drivingtether of the first aft set is coupled to a first location on an insideface of the aft paddle, engages and traverses the first aft upperpulley, and couples to a first aft winch portion, wherein the drivingtether of the first aft set is wound onto the first aft winch portion ina first direction, wherein the retrieval tether of the first aft set iscoupled to a second location on an outside face of the aft paddle,engages and traverses the first aft bottom pulley, traverses through thefirst aft port and exits the inside face of the aft paddle, engages andtraverses the second aft upper pulley, and couples to a second aft winchportion, wherein the retrieval tether of the first aft set is wound ontothe second aft winch portion in a second direction, wherein the drivingtether of the second aft set is coupled to a third location on theoutside face of the aft paddle, engages and traverses the second aftbottom pulley, traverse through the second aft port and exits the insideface of the aft paddle, engages and traverse the third aft upper pulley,and coupled to a third aft winch portion, wherein the driving tether ofthe second aft set is wound onto the third aft winch portion in thefirst direction, wherein the retrieval tether of the second aft set iscoupled to a fourth location on the inside face of the aft paddle,engages and traverses a fourth aft upper pulley, and couples to thefourth aft winch portion, wherein the retrieval tether of the second aftset is wound onto the fourth aft winch portion in the second direction.15. The converter of claim 14, wherein when the aft paddle moves up theaft guide rails, the driving tether of the second aft set causes thethird aft winch portion to rotate in the first direction, wherein therotation of the third aft winch portion in the first direction causesthe shaft to rotate in the first direction, wherein the rotation of theshaft in the first direction generates electricity through the powergenerator, wherein the rotation of the third aft winch portion in thefirst direction causes the fourth aft winch portion to rotate in thefirst direction, wherein the rotation of the fourth aft winch portion inthe first direction causes the retrieval tether of the second aft set towind onto the fourth aft winch portion, wherein the retrieval tether ofthe first aft set causes the second aft winch portion to rotate in thesecond direction, wherein the first aft one-way clutch prevents therotation of the shaft when the second aft winch portion rotates in thesecond direction, wherein the rotation of the second aft winch portionin the second direction causes the first aft winch portion to rotate inthe second direction, and the rotation of the first aft winch portion inthe second direction causes the driving tether of the first aft set towind onto the first aft winch portion.
 16. The converter of claim 15,wherein when the aft paddle moves down the forward guide rails, thedriving tether of the first aft set causes the first aft winch portionto rotate in the first direction, wherein the rotation of the first aftwinch portion in the first direction causes the shaft to rotate in thefirst direction, wherein the rotation of the shaft in the firstdirection generates electricity through the power generator, wherein therotation of the first aft winch portion in the first direction causesthe second aft winch portion to rotate in the first direction, whereinthe rotation of the second aft winch portion in the first directioncauses the retrieval tether of the first aft set to wind onto the secondaft winch portion, wherein the retrieval tether of the second aft setcauses the fourth aft winch portion to rotate in the second direction,wherein the second one-way clutch prevents the rotation of the shaftwhen the fourth aft winch portion rotates in the second direction,wherein the rotation of the fourth aft winch portion in the seconddirection causes the third aft winch portion to rotate in the seconddirection, and wherein the rotation of the third aft winch portion inthe second direction causes the driving tether of the second aft set towind onto the third aft winch portion.